Substrate Discrimination by Cholapod Anion Receptors: Geometric Effects and the "Affinity-Selectivity Principle"

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• 作者：John P. Clare ; Alan J. Ayling ; Jean-Baptiste Joos ; Adam L. Sisson ; Germinal Magro ; M. Nieves Pé ; rez-Payá ; n ; Timothy N. Lambert ; Rameshwer Shukla ; Bradley D. Smith ; and Anthony P. Davis
• 刊名：Journal of the American Chemical Society
• 出版年：2005
• 出版时间：August 3, 2005
• 年：2005
• 卷：127
• 期：30
• 页码：10739 - 10746
• 全文大小：156K
• 年卷期：v.127,no.30(August 3, 2005)
• ISSN：1520-5126

文摘

Cholapod anion receptors can achieve high affinities while maintaining compatibility with nonpolarmedia. Previously they have been shown to transport anions across cell and vesicle membranes. In thepresent work, the scope of the architecture is expanded and structure-selectivity relationships areinvestigated. Eight new receptors have been synthesized, with up to six H-bond donor centers. Using Cram'sextraction method, these compounds plus five known examples have been tested for binding to sevenmonovalent anions (tetraethylammonium salts, wet chloroform as solvent). Association constants in excessof 10¹⁰ M^-1 have been measured for several pairings. Selectivities vary with receptor geometry, as expected.More remarkably, they also depend on receptor strength: more powerful receptors show a wider range ofbinding free energies, and therefore a greater spread of K_a(X^-)/K_a(Y^-). This "affinity-selectivity" effect canbe derived from empirical relationships for H-bond strengths, and could prove widely operative insupramolecular chemistry.